"Peek not through a keyhole, lest ye be vexed"
I recall reading this a while ago in Stephen King's Duma Key. The character said their mother always said it when they were a kid. On the internet, the only source was Stephen King, but I can't help but feel that it's been said somewhere else.
Also, my first language not being English, does this really explain what it means:
Don't look too far into things or you will find something that you do not like/did not expect.
Anyway, for some reason ever since I read that quote, I keep reciting it in my head whenever I am upset or unhappy with someone. Does anybody else recite things in their head, given certain situations? It sometimes calms me.